The second season's announcement trailer, released on August 31, 2016, listed the tentative titles for all nine episodes. [3] Episode eight was likely originally titled "The Brain", although major inconsistencies between the initial and final titles make this impossible to confirm. The episode's official title was revealed on October 27, 2017. Eleven and her friends began investigating Billy after they realised he had been acting strange; after confronting him at the Hawkins Community Pool, the group realised he had fell under the Mind Flayer’s control. Later, Eleven used psychic projection to locate Billy after he escaped their encounter. However, to Eleven’s surprise, Vecna was aware of her presence within Billy's mind, and placed her in a hallucination; using Billy as a vessel, Vecna talked to Eleven and learned of her location. However, in this moment of psychic connection between Eleven, Billy and Vecna, Eleven also saw Billy’s childhood memories, and learned of his troubled past. [4] The Party initially believed that the Mind Flayer commanded the Upside Down's hive mind, and was the consciousness that possessed Will Byers and Billy Hargrove. From 1984 to 1986, the group and their allies tended to call the Mind Flayer "him" and "he"; they knew little else about the creature, besides 'his' intention to eradicate humanity and merge the human world with the Upside Down. In March 1986, Eleven, Will, Nancy and the others realized that the 'he' in control of the hive mind was actually Vecna, and had used the Mind Flayer organism to create the hive mind.

Despite having an episode named after it, the Mind Flayer is not physically present in said episode. Waffle cards don’t do anything in the game specifically, but if you want to play a series of games, you can keep points and waffles are worth 1 point.

While a massively powerful being, the Mind Flayer was not without weakness. Most notably, it had a low tolerance to heat, particularly fire. All hosts within its hive mind shared this weakness, resulting in the creature feeling pain whenever a connected entity was exposed to heat, or burned.

Though Vecna's control of the Mind Flayer's hive mind made him powerful, the two-way nature of the psychic connection was also a point of vulnerability. Any pain felt by the connected entities was shared amongst them; the physical suffering of his thralls would translate to every other being in the hive mind, including Vecna himself. This made the hive mind a prime target for his enemies. Certain cards drive a player closer to becoming possessed and joining the mind flayer team, while other cards cancel out these other negative cards. So during the game if you are sane, whenever you receive 3 mind flayer cards, you become possessed. But for each memories card you have, it cancels out a mind flayer card. So if you have memories cards, you are allowed to have more mind flayer cards in your hand before you become possessed. I sold about 12,000 copies of the game, and eventually decided to send a bunch of copies to bigger publishers as I was nervous that I would never get a distribution deal otherwise. I hired a wonderful Dutchman named Richard to demo the game at SPIEL '19, and he attracted the interest of Repos Production, which shortly afterward became a subsidiary of Asmodee.I hadn't gotten to season 3 yet, but the Mind Flayer seemed to be an obvious match for the game, so Repos paired with another Asmodee subsidiary named Mixlore to make the licensing deal with Netflix, then a talented developer at Repos named Pierre began percolating ideas. After taking Will to Hopper's cabin, Joyce, Nancy, and Jonathan restrained him, surrounding him with numerous heaters. This eventually caused the fragment of the Mind Flayer possessing Will to be expelled from his body. The particles fled the cabin, escaping to the abandoned Brimborn Steel Works to lay low. When Vecna emerged as a new threat to Hawkins in 1986, Dustin believed that he was essentially the Mind Flayer's "five-star general". Later, Vecna targeted Nancy Wheeler with the sole purpose of sending Eleven a message. He subjected Nancy to various disturbing visions, including a "giant creature with a gaping mouth" looming over Hawkins. Hopper and his allies returned to the base, hoping that destroying the particles in the cell could inflict damage to the Upside Down’s hive mind, and therefore assist in the conflict simultaneously occurring in Hawkins. After learning what had happened since their escape, the group started fighting the possessed creatures, still hoping to inflict pain on the hive mind. After chasing Hopper and Joyce around the Soviet base for a lengthy period, the Demogorgons gathered in the same spot, allowing Murray to burn the bulk of them to death with Yuri Ismaylov's flamethrower. The fully grown Demogorgon survived, but moments later, Hopper used a sword to behead the creature. The deaths of the Demogorgons weakened everything else connected to the hive mind: the bats, the vines, and even Vecna himself. By executing the Demogorgons, the group seemed to destroy various fragments of the Mind Flayer, or otherwise rendered its particles unusable. In Dungeons and Dragons, Mind Flayers are a race of psychic humanoids with tentacles on their faces who eat brains. They primarily use their powerful psychic abilities to mentally enslave other beings. More recent editions have given the Mind Flayers the proper name "Illithids".

Prolonged exposure to high temperature can weaken the Mind Flayer. When Will Byers was exposed to high temperature, it forced the fragment of the Mind Flayer within Will to flee his body. Similarly, when soldiers set the tunnels aflame, the possessed Will writhed in pain.The entity was gigantic, looming at least fifty stories tall [1], and sported a distinctive spider-like appearance. The Mind Flayer exercised supreme control of the Upside Down via a psychic link, with Demogorgons, vines, and Demobats forming a shared hive mind; for a period in 1985, possessed humans known as "the Flayed" also comprised part of the hive mind. In a sense, the entirety of the Upside Down was like one gigantic organism, with all its contents and agents mentally connected via the Mind Flayer.